CVE-2021-40828

TLS hostname validation issues within AWS IoT Device SDKs on Windows

6.3 MediumFix available

Connections initialized by the AWS IoT Device SDK v2 for Java (versions prior to 1.3.3), Python (versions prior to 1.5.18), C++ (versions prior to 1.12.7) and Node.js (versions prior to 1.5.1) did not verify server certificate hostname during TLS handshake when overriding Certificate Authorities (CA) in their trust stores on Windows. This issue has been addressed in aws-c-io submodule versions 0.9.13 onward. This issue affects: Amazon Web Services AWS IoT Device SDK v2 for Java versions prior to 1.3.3 on Microsoft Windows. Amazon Web Services AWS IoT Device SDK v2 for Python versions prior to 1.5.18 on Microsoft Windows. Amazon Web Services AWS IoT Device SDK v2 for C++ versions prior to 1.12.7 on Microsoft Windows. Amazon Web Services AWS IoT Device SDK v2 for Node.js versions prior to 1.5.3 on Microsoft Windows.

Attack profile

How easy it is to exploit

Attack vector: Adjacent network
Complexity: High
Privileges needed: High
User interaction: Required

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

0.41%Down 0.9 points since Nov 23, 2021

What each source reports

CVE List Score used 6.3

TLS hostname validation issues within AWS IoT Device SDKs on Windows

Record: CVE-2021-40828
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
Updated: 2026-11-02

EUVDEUVD-2021-0028 6.3

Record: EUVD-2021-0028
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
Updated: 2026-11-03

GitHub AdvisoriesGHSA-94jq-q5v2-76wj 5.4

Improper certificate management in AWS IoT Device SDK v2

Record: GHSA-94jq-q5v2-76wj
CVSS 4.0: 5.4 MediumCVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
Weakness: CWE-295
Updated: 2026-11-02

NVD 6.3

Record: CVE-2021-40828
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
CVSS 3.1: 8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0: 5.8 MediumAV:A/AC:L/Au:N/C:P/I:P/A:P
Weakness: CWE-295
Updated: 2026-11-02

OSV 8.8

Record: CVE-2021-40828
CVSS 3.1: 8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-07

OSVGHSA-94jq-q5v2-76wj 5.4

Improper certificate management in AWS IoT Device SDK v2

Record: GHSA-94jq-q5v2-76wj
CVSS 4.0: 5.4 MediumCVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 6.3 MediumCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
Weakness: CWE-295
Updated: 2026-11-02

OSVPYSEC-2021-861 No score

Record: PYSEC-2021-861
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`software.amazon.awssdk.iotdevicesdk:aws-iot-device-sdk` Maven	before 1.3.3	1.3.3
`aws-iot-device-sdk-v2` npm	before 1.5.1	1.5.1
`awsiotsdk` PyPI	before 1.5.18	1.5.18
`software.amazon.awssdk.iotdevicesdk:aws-iot-device-sdk` Maven	before 1.3.3, plus listed versions 0.2.30.2.40.2.50.2.60.2.7 Show 39 moreShow less 0.2.80.3.00.3.10.3.20.3.31.0.01.0.11.0.21.0.31.0.41.0.51.0.61.0.71.0.81.0.91.1.01.1.11.2.01.2.11.2.101.2.111.2.121.2.131.2.141.2.151.2.161.2.171.2.181.2.21.2.31.2.41.2.51.2.61.2.71.2.81.2.91.3.01.3.11.3.2	1.3.3
`awsiotsdk` PyPI	before 1.5.18, plus listed versions 0.2.40.2.90.3.01.0.21.0.3 Show 26 moreShow less 1.0.51.0.61.1.01.2.01.2.11.3.01.3.11.3.21.4.01.5.01.5.11.5.101.5.111.5.121.5.131.5.141.5.151.5.161.5.171.5.21.5.31.5.41.5.51.5.61.5.71.5.8	1.5.18

History

History
Recorded	Changed	Sources
Nov 5, 2026	facts	OSV
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-40828 is a medium vulnerability (CVSS 6.3) in Amazon Web Services Aws Iot Device Sdk V2 For C++, published November 22, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.41%, the 35th percentile. Fixed in software.amazon.awssdk.iotdevicesdk:aws-iot-device-sdk 1.3.3.

References

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